我要读取表A中的所有字段，同时得到字段sum(Grade) as GrageSum,按StudentName分组的，就是说相等StudentName，只取出其中一行数据，但是要汇总相等StudentName所有的Grade，谢谢！
------解决方案--------------------
select studentname,sum(grade),max(col1),max(col2),...max(coln)
from tb
group by studentname
------解决方案--------------------
select studentname,col1,col2,..., --写全字段，除了grade
(select sum(grade) from tb where studentname=a.studentname) as grade
from tb a
where not exists (
select 1 from tb
where studentname=a.studentname
and key <a.key
)